I am having a hot idle problem on my 1998 D1. When first started when the vehicle has been ran, the idle stumbles until I start driving. This happens at every startup when the engine is hot. No coolant leaking, no check engine light, changed plugs. The truck does not stall, it just stumbles when at idle. It is weird, because it goes away once I start driving.I am looking into the wires, but I only have 87k and saw no sparks at night with the hood open. I am thinking this could be the IAC, or the fuel temp sensor. Any suggestions where to start.

 

When was it last tuned along with wires, what octane gas are you running? Try cleaning the t/body and the IAC for sure.

 

Had the same thing...FTS solved most of the problem. Found additional problems with the TPS "heat soaking" (after a hot drive and sitting for about 30 min, the parameters would seem to float around when using the scan tool)...once replaced, the problem cleared up.

 

TPS = Throttle Position Sensor?

What is IAC? FTS?

 

Sorry...

IAC - Idle Air Control motor (stepper motor)
FTS - Fuel Temperature Sensor

Was a former "Mr. Goodwrench" GM/ASE Certified technician many years ago and the "lingo" is a little different...my apologies!!!

 

I am going to replace the wires, and clean the IAC (stepper motor). Any tips for cleaning the IAC? I have some maf cleaner and plan to blast it clean. I heard the MAF on the D1 can be damaged by cleaning is this correct even if using maf cleaner? Running 93 octane gas.

 

Don't know anything about the stepper motor either. Take some good pics while you are tearing into the problem. It will be good to see what you find.

Love those DI's. I try to keep mine going as smooth as possible. Let us know what you find. There's too many DI's going to waste not to keep them up.

 

Go to the write up section, there is a write up on how to clean the t-body on aDI.
The IAC is the thing closest to the butterfly, remove it without moving the pluger, you move it and your screwed because it is calibrated.
Clean all around in there making sure all ports are clear.

But your problem is a bad fuel temp sensor.

 

You can clean the MAF on a D1 if you are careful. You can not on a D2.

 

Thanks for the tip not to move the plunger. I would have moved it to clean it since I do this with my ford expedition IAC. I will look into the FTS, where is it located? I may clean the MAF b/c it does look kinda dirty since the last owner did not do proper air filter changes.